Below is a sorted stem-and-leaf diagram for the measured speeds (miles per hour) of 49 randomly chosen vehicles on highway 1-80 in Nebraska. Which is the modal class? Stem unit = 10 Leaf unit = 1 Frequency Stem Leaf 1 4 9 5 5 17 0 1 2 2 2 4 5 5 5 5 6 6 8 8 9 9 9 19 0 1 1 1 2 3 3 3 4 5 6 6 6 7 7 8 9 9 9 7 01 3 3 5 5 7 1 00 4 012 2 49Multiple Choice O 60 but less than 70. 70 but less than 80. 80 but less than 90. 000 It is impossible to determine